Geologists have been uncertain about how much shale gas is locked in UK deposits but concerns are mounting that the process of releasing it by creating fissures up to 10,000ft underground with rock-dissolving chemicals and high-pressure water will damage the local environment and increase climate emissions.

Test drilling for shale gas by Cuadrilla Resources started near Blackpool in March but was suspended following two small earthquakes in the area, one in April and one in May, which occurred around the time the company was injecting fluids under pressure. The company said there was no connection between the drilling and the quakes but some geologists doubted this.

"It is deeply irresponsible to try to extract this gas. It is a dirty, dangerous and dodgy energy supply which is still not understood well enough", said Green party leader Caroline Lucas at a meeting in London on Tuesday.

Camp Frack, as the camp is being called, will set up near the village of Singleton in a field donated by a farmer next to the drilling site. Organisers said they had no idea how many people might come but did not expect it to be on the same scale as the five previous Climate Camps.

Vast potential supplies of shale gas in the US have led the gas industry to argue that shale gas could be a "transitional alternative" to coal because it emits around 15% less greenhouse gas emissions than coal and could supply the US for hundreds of years.

But Kevin Anderson, deputy director of Manchester University's Tyndall centre for climate change research, warned that the gas should not be seen as an alternative. "It is not a substitute. My fear is that it will be combusted as well as coal. It is an addition," he said.

The former environment minister Michael Meacher, speaking at the event on Tuesday, warned of a vast worldwide expansion of shale gas, with the industry expecting 35% of the increase in all gas production by 2035 to come from shales. "That is a huge shift from conventional fossil fuels to unconventional sources. But it is a big risk because the US industry is very poorly regulated and companies do not have to disclose the chemicals that they use," he said.